The one of 480-479 BCE.
The Persian Empire .
Yes.
The Persian king, and first Sparta then Athens on the Greek side.
The Persian Wars
Its Leonidas, king of Sparta during the Persian wars.
Self defence.
It led the successful resistance to the Persian invasion 480 to 479 BCE.
The Persian Wars 490 to 449 BCE.
Sparta led a coalition of Peloponnesian city-states which we today call the Peloponnesian League. It was already in existence before the Persian Wars - comprising the Dorian city-states of southern Greece.
The Persian Empire and an alliance of Greek city-states led first by Sparta and then Athens.
It led the anti-Persian alliance of Greek city-states.
The Persian Empire versus a coalition of Greek city-states, at first led by Sparta, then by Athens.